This post is in response to a comment on a thread by Ogremasch (https://artemis.forumchitchat.com/post/update-dmx-basics-guide-9994591?pid=1307071430). Ogremasch noted that a lot of hardware with guides in the forum is hard to find commercially, if at all. My own experience with an off-the-shelf DMX-USB interface was less than stellar. Artemis needs an FTDI chip for the USB interface if using the DMX output that comes directly from the game. That also limits the choices. Some hardware sold with FTDI chips are using counterfeit chips, which don't always work.

Looking at what the USB interface does, and noting people's preference for an RJ45 jack, I have sketched up the following interface design. It needs some testing, but should be up to the task.

I would be interested in testing it out if you make a spare one, let me know and I'll paypal you for the time and materials.

If I am reading this correctly, this would be a single box that takes USB and Power and gives the user DMX out through RJ45 right? I am not great at reading schematics (yet).

Is there a distance limitation to using RJ45 ( I know that ethernet cables can ony be about 300 feet long for internet use and the max effective length of USB is about 16 feet, I am not sure if DMX has a similar limitation. the likely hood of having a 300 foot cable run is likely very small but I wanted to ask since I am new to the DMX stuff and you have experience with it. I have also heard of people in the Forums having trouble with their DMX that may be linked to the USB being too long. I have limited my DMX USB cable to 3 feet to avoid that problem which means I will need to apply the length to the DMX side of the board which leads me to needing to know if there is a max limit my server PC can be away from my bridge and still effectively control lights with relatively little or no perceivable lag.

Originally Posted by ogremaschI would be interested in testing it out if you make a spare one, let me know and I'll paypal you for the time and materials.

If I am reading this correctly, this would be a single box that takes USB and Power and gives the user DMX out through RJ45 right? I am not great at reading schematics (yet).

I was originally just thinking about a replacement for the basic USB-to-DMX interface using an RJ45 jack for the DMX part. Having power on there seems like a good idea, so I added it:

I put a 2.1 mm DC barrel jack on there so power can be provided at whatever voltage needed. Per Power-Over-Ethernet convention, I have assigned the RJ45 pins as follows:1: D+ (data)2: D- (data)4 and 5: +Volt7 and 8: ground

I plan to make one in the near future. I'll let you know how it goes.

Quote:

Originally Posted by ogremasch

Is there a distance limitation to using RJ45 ( I know that ethernet cables can ony be about 300 feet long for internet use and the max effective length of USB is about 16 feet, I am not sure if DMX has a similar limitation. the likely hood of having a 300 foot cable run is likely very small but I wanted to ask since I am new to the DMX stuff and you have experience with it. I have also heard of people in the Forums having trouble with their DMX that may be linked to the USB being too long. I have limited my DMX USB cable to 3 feet to avoid that problem which means I will need to apply the length to the DMX side of the board which leads me to needing to know if there is a max limit my server PC can be away from my bridge and still effectively control lights with relatively little or no perceivable lag.

I look forward seeing more in this thread as the project develops.

300 feet sounds about right. Because DMX uses RS485 protocol, which is a differential pair for signal, typically in twisted pair wire (such as cat 5 cable), it can go longer than any of us are likely to use up. As far as I can tell, it doesn't generate a lot of errors.

USB has a pretty short length limitation as you noted. Shorter is better. Otherwise, boosters are needed.

PCB arrived today. Assembly was a breeze and the new interface works beautifully. I loaded up Artemis using the default DMX commands. The DMX controller and LED strip that Thom and Mark gave me at Armada III (DMX workshop - highly recommended!) worked perfectly.

300 feet sounds about right. Because DMX uses RS485 protocol, which is a differential pair for signal, typically in twisted pair wire (such as cat 5 cable), it can go longer than any of us are likely to use up. As far as I can tell, it doesn't generate a lot of errors.

USB has a pretty short length limitation as you noted. Shorter is better. Otherwise, boosters are needed.

Great work as usual, Angel! - RS485 is tremendously useful - and that's why I use the SN75176 in my Arduino design. (TekNynja validated the SN75176 pair in his design, good out to 100 meters, so your 300 foot figure is good at a minimum) Lets me get that Arduino signal out over a good long distance. I got so frustrated at trying to figure it all out over USB to my Arduino, though, so I just switched to ArtNet 😉

This should be a great, easy to make project for a lot of people to get cranking with some DMX for low money, and not a Ton of learning needed. I think its a huge contribution to the community, so thank you!

Going to have a party at the house on 2/9 - should have enough people and computers to run 2 bridges. Contemplating the risk/reward percentage of asking my wife if its ok for me to build out a second lighting rig 😉I will definitely take some extensive video this time. I swear!!!!

I now have three USB-to-DMX interfaces that are built and tested with Artemis. I am very happy with the performance of these custom-built interfaces.

Doing some searching online, it looks like all the commercially-available DMX decoders (i.e., the box you need to plug the LEDs into), have the power supply attached with something other than the RJ45 jack (i.e., ethernet cable). Therefore, having the power jack on this board only benefits people who can make there own decoder boards, which entirely defeats the purpose of me making them. Therefore, the power jack is out of the final design.

In the interests of helping my fellow hobbyists, I have decided to follow through on a suggestion received here and sell these interfaces. I am looking at using Etsy as the selling platform, since they are setup for homemade stuff like this and I don't want to run a store.

tested to work with Artemis (i.e., the shield, red alert, etc. cues that ship with the game all work as they are supposed to)

I am currently looking at shipping to points in the US. All inclusive, I think I can get 1 assembled interface board with no-frills pressboard base shipped to US buyers for $25.50. Maybe I can get the shipping down to make it less -- we'll see.

Why would anyone want these when there are cheaper interfaces for sale?

Ethernet jack is built in and wired to work with popular DMX decoders -- less wires for someone to figure out.

Insert Photos

Web address (URL)

Image URL

If your URL is correct, you'll see an image preview here. Large images may take a few minutes to appear.
Remember: Using others' images on the web without their permission may be bad manners, or worse, copyright infringement.